In order to reduce the thermal resistance of heat transfer devices which support the cooling of laser diode bars, it is known for example from the patent and unexamined patent applications U.S. Pat. No. 5,325,384, WO 2006 098 897 A1 and WO 2007 082 508 A1 to attach heat conducting bodies to opposing sides of the laser bar. If the heat removal capacity of the heat conducting bodies is different—for example because the heat sinks connected to the heat conducting bodies have a clearly different thermal resistance, the thermal resistance of the heat transfer device can be reduced by bringing both heat conducting bodies into thermal connection with each other in heat transfer sections beside the laser diode bar, with the result that a part of the heat of the more poorly cooled heat conducting body can be absorbed by the better cooled one. In extreme cases, only one of the heat conducting bodies is connected to a heat sink and must absorb virtually all of the heat of the laser diode bar absorbed by the other heat conducting body. Such an arrangement is known from publication no. 68760Q from Proc. SPIE vol. 6876 (2008) in which, in order to achieve a good thermal connection between the heat conducting bodies, a thermally highly conductive electrically insulating aluminium nitride ceramic plate was soldered with the help of two metallic solder layers on the side of the laser diode bar facing away from the light emission between the epitaxy-side metallic heat removal body and the substrate-side metallic heat conducting body.
With this and similar arrangements, there is the problem that the highly heat conductive intermediate element which is arranged between the heat transfer sections of the heat conducting bodies should preferably have the same thickness as the laser diode bars between its two sides, which are connected by heat absorbing sections of the heat conducting bodies for heat dissipation, in order that the thickness of the joining zones between the laser bar and the heat absorbing sections of the heat conducting bodies on the one hand and between the intermediate element and the heat transfer sections of the heat conducting bodies on the other hand can be kept the same on the one hand and kept constant over the extent of each joining zone on the other hand.
A constant, uniform and in particular small joining zone thickness is essential in particular for the connection of the laser diode bar in order to ensure a uniform quality and reliability of the diode laser that is both thermally and also electrically and optically highly loaded. The thickness of laser diode bars is different both within a batch and between several batches. The same applies to the intermediate elements. A reproducible matching of the thicknesses of laser diode bars and intermediate elements to less than 2 μm difference is either costly in production terms or accompanied by a time-consuming selection and allocation process.